Music: Björn again? Abba's perfect parting gift

It was something even ardent Abba fans thought would never happen: all four original members performing on stage together again. For years after they split, the Swedes were offered enormous sums of money to reform for a comeback tour, but every overture was rebuffed.

It was something even ardent Abba fans thought would never happen: all four original members performing on stage together again. For years after they split, the Swedes were offered enormous sums of money to reform for a comeback tour, but every overture was rebuffed.

This time, they were gathered in front of 500 friends and associates in Stockholm as they celebrated the 50th anniversary of their first getting together. Back in 1966, they were known by an unwieldy moniker made up of their first names - Björn & Benny, Agnetha & Anni-Frid - and were hardly to know, as they took their first tentative steps, that they would go on to be one of the best-selling pop acts the world has ever known.

While stranger things have happened, I would be shocked if they reformed in any meaningful way. Some things are best left alone: a pity nobody told the Stone Roses, judging from the pedestrian pair of new songs they've foisted on the world.

No, far better to remember Abba when they were in their pomp - not just at the height of their late 70s sales period, when they were ripping up the charts with every single they released, but at the very end of their career in 1981 when they were in the most creative and daring form of their lives. That was the year they give the world The Visitors, an album that was dark and troubled and thrilling and a perfect parting gift. Best, after all, to go out on a high.

By the time the sessions kicked off in March of that year, both Björn and Agnetha's marriage together, plus Benny's and Anni-Frid's, had come to an end. The former pair had divorced in 1980, but the latter two announced their separation just a month before going into the studio. Not surprisingly, there was more tension than usual during the sessions with Björn subsequently suggesting the atmosphere could be "frosty" on occasion.

The mood was hardly helped by the fact that the male duo - who were the chief songwriters - turned up with a handful of songs that were focused on splintered relationships and how one member always comes out of these splits better. The album's most commercially arresting song, 'One of Us' featured Agnetha singing words penned by her ex-husband that suggested the female partner, newly freed from a relationship, was regretting her independence.

The year before, on 1980's Super Trooper album, she also had to sing what must have been the painful words of 'The Winner Takes it All' - one of her very finest vocal performances.

There was an air of melancholy on much of the album, not least 'Slipping Through My Fingers', on which a parent rues how little time they've spent with their child during those precious early years. It was sung by Agnetha and was inspired by Linda, the daughter she had with Björn, who was seven at the time.

And there was the sort of maturity in songwriting that makes it almost inconceivable that the same quartet were behind the ghastly 'Dum Dum Diddle' just five years before. 'When All is Said and Done' is the sort of sophisticated pop song that Abba did better than almost any of their peers.

The Visitors also reflected the uncertain political times of the era with the arresting title track, which opens the album, eerily capturing the sense of unease in life behind the Iron Curtain. "I hear the doorbell ringing," sings Anni-Frid, her vocals heavily treated, "and suddenly the panic takes me".

The sonic backdrop was evocative and exotic and still distinctly Abbaesque. Benny and Björn produced the album but as with so many other defining Abba moments, the wonderful textures of sound were painstakingly created by the engineer, Michael Tretow. Not every track on The Visitors was a masterpiece, though. One of Abba's great weaknesses was their willingness to leave filler on all their albums, and it's hard to make the case for the hokey 'Two for the Price of One', which seemed to be about a half-hearted attempt to organise a threesome.

The original album boasted nine tracks and in the years since, several bonus songs have been added to expanded editions, with the deluxe version from 2012 featuring several excellent additions. 'Cassandra' is in the same ballpark as the title track -an unsettling and cryptic song about a troubled society - while 'Should I Laugh or Cry' offers something of a revenge for Agnetha and Anni-Frid as they sing about a boorish husband who wrecks his own marriage. They're a pair of songs that really should have made the original track-listing.

Although the writing was on the wall for those who looked hard enough, few realised it would be their swansong. There was no grand announcement of a split - the band simply faded away and, in Agnetha's case, disappeared from view altogether.

Their final televised performance was a cringe-worthy interview on Noel Edmonds' Late Late Breakfast Show: looking back on it now, it seems obvious that they were thoroughly sick of the demands of being in a band together.

In all, six singles were released from the album and 'One of Us' would give them their final number one in several territories, including Ireland. But it performed disastrously in the US, failing to break into the top 100. That it was released a year after the album came out and when Abba were effectively over didn't help, but it did give some indication of their declining fortunes in an era where many still dismissed the quartet of being purveyors of throwaway pop.

Incidentally, The Visitors has the distinction of being the first album ever pressed for compact disc, in the summer of 1982 - although Billy Joel's 52nd Street, originally released four years before, would pip it to the post when it came to the honour of first released on the format that would be the most dominant by far for the next two decades.